U.S. patent application number 09/982585 was filed with the patent office on 2003-04-17 for self adjusting clocks in computer systems that adjust in response to changes in their environment.
Invention is credited to Belady, Christian L., McClendon, Thomas W..
Application Number | 20030074591 09/982585 |
Document ID | / |
Family ID | 25529318 |
Filed Date | 2003-04-17 |
United States Patent
Application |
20030074591 |
Kind Code |
A1 |
McClendon, Thomas W. ; et
al. |
April 17, 2003 |
Self adjusting clocks in computer systems that adjust in response
to changes in their environment
Abstract
An electronic device such as a computer, circuit board, or
integrated circuit is built including circuitry for receiving
temperature information. The clock frequency of the electronic
device is varied in response to the temperature of the electronic
device, thus lowering speed and power consumption of the device
during periods of higher than normal temperature. Alternately, an
electronic device such as a computer, circuit board, or integrated
circuit is built including circuitry for receiving power supply
information. The clock frequency and possibly the power supply
voltage of the electronic device is varied in response to the power
supply status of the electronic device, thus lowering speed and
power consumption of the device during periods of lower than normal
power supply current capability.
Inventors: |
McClendon, Thomas W.;
(Plano, TX) ; Belady, Christian L.; (McKinney,
TX) |
Correspondence
Address: |
HEWLETT-PACKARD COMPANY
Intellectual Property Administration
P.O. Box 272400
Fort Collins
CO
80527-2400
US
|
Family ID: |
25529318 |
Appl. No.: |
09/982585 |
Filed: |
October 17, 2001 |
Current U.S.
Class: |
713/322 |
Current CPC
Class: |
Y02D 10/126 20180101;
G06F 1/324 20130101; Y02D 10/16 20180101; Y02D 10/00 20180101; G06F
1/3203 20130101; G06F 1/206 20130101 |
Class at
Publication: |
713/322 |
International
Class: |
G06F 001/26 |
Claims
What is claimed is:
1. An electronic device comprising: a temperature sensor; and a
clock controller electrically coupled with said temperature sensor,
wherein said clock controller receives a temperature signal from
said temperature sensor and produces clock signals of varying
frequencies in response to said temperature signal.
2. The electronic device of claim 1, wherein said clock signals
increase in frequency in response to a decrease in said temperature
signal, and said clock signals decrease in frequency in response to
an increase in said temperature signal.
3. The electronic device of claim 1, wherein said electronic device
is a computer.
4. The electronic device of claim 1, wherein said electronic device
is an integrated circuit.
5. The electronic device of claim 4, wherein said temperature
sensor is a thermal diode.
6. The electronic device of claim 1, wherein said clock includes a
phase-locked loop.
7. The electronic device of claim 6, wherein said phase-locked loop
is digital.
8. The electronic device of claim 1, wherein said clock
automatically changes frequencies during normal operation of said
electronic device.
9. An electronic device comprising: a power supply failure
detector; and a clock electrically coupled with said power supply
failure detector, wherein said clock receives a power fail signal
from said power supply failure detector and produces clock signals
of varying frequencies in response to said power fail signal.
10. The electronic device of claim 9, wherein said clock signals
decrease in frequency in response to said power fail signal.
11. The electronic device of claim 9, wherein said electronic
device is a computer.
12. The electronic device of claim 9, wherein said electronic
device is an integrated circuit.
13. The electronic device of claim 12, wherein said power supply
failure detector is built into a power supply.
14. The electronic device of claim 9, wherein said clock includes a
phase-locked loop.
15. The electronic device of claim 9, wherein said clock
automatically changes frequencies during normal operation of said
electronic device.
16. An electronic device comprising: a power supply failure
detector; and a power supply controller of said electronic device
electrically coupled with said power supply failure detector,
wherein said power supply controller adjusts a power supply voltage
in response to said power fail signal.
17. A method for adjusting the operation of an electronic device
comprising the steps of: a) reading a temperature value of said
electronic device; and b) automatically setting said clock
frequency in response to said temperature value.
18. The method for adjusting the operation of an electronic device
of claim 17, wherein said clock frequency is automatically set to a
first frequency in response to a first temperature value, and said
clock frequency is automatically set to a second frequency in
response to a second temperature value.
19. The method for adjusting the operation of an electronic device
of claim 18, wherein said first frequency is less than said second
frequency when said first temperature is greater than said second
temperature.
20. The method for adjusting the operation of an electronic device
of claim 18, wherein said first frequency is greater than said
second frequency when said first temperature is less than said
second temperature.
21. A method for adjusting the operation of an electronic device
comprising the steps of: a) detecting a power supply failure; and
b) automatically setting a clock frequency for said electronic
device in response to said power supply failure.
22. The method for adjusting the operation of an electronic device
of claim 21, wherein said clock frequency is automatically set to a
first frequency during normal operation, and said clock frequency
is automatically set to a second frequency in response to a power
supply failure.
23. The method for adjusting the operation of an electronic device
of claim 22, wherein said first frequency is greater than said
second frequency.
24. A method for adjusting the operation of an electronic device
comprising the steps of: a) reading a first temperature value; b)
reading a new temperature value; c) comparing said new temperature
value to said first temperature value; d) increasing a clock
frequency when said new temperature value is less than said first
temperature value; and e) decreasing a clock frequency when said
new temperature value is greater than said first temperature
value.
25. The method for adjusting the operation of an electronic device
of claim 24, further comprising the step of: f) replacing said
first temperature value with said new temperature value.
26. The method for adjusting the operation of an electronic device
of claim 25, further repeating steps b) through f) at least once
during operation of said electronic device.
27. The method for adjusting the operation of an electronic device
of claim 25, further repeating steps b) through f) continually
during operation of said electronic device.
28. A method for adjusting the operation of an electronic device
comprising the steps of: a) detecting a power fail signal; and b)
decreasing a clock frequency when said power fail signal is
detected.
29. The method for adjusting the operation of an electronic device
of claim 28, further comprising the step of: c) decreasing a power
supply voltage when said power fail signal is detected.
30. The method for adjusting the operation of an electronic device
of claim 29, further repeating steps a) through b) at least once
during operation of said electronic device.
31. The method for adjusting the operation of an electronic device
of claim 29, further repeating steps a) through b) continually
during operation of said electronic device.
32. An electronic device comprising: means for measuring a
temperature of said electronic device; means for adjusting a clock
frequency in response to said temperature of said electronic
device.
33. The electronic device of claim 32, wherein said means for
adjusting a clock frequency increases said clock frequency in
response to a decrease in said temperature, and said means for
adjusting a clock frequency decreases said clock frequency in
response to an increase in said temperature.
34. The electronic device of claim 32, wherein said electronic
device is a computer.
35. The electronic device of claim 32, wherein said electronic
device is an integrated circuit.
36. The electronic device of claim 35, wherein said means for
measuring a temperature is a thermal diode.
37. The electronic device of claim 32, wherein said means for
adjusting a clock frequency includes a phase-locked loop.
38. The electronic device of claim 32, wherein said means for
measuring a temperature and said means for adjusting a clock
frequency automatically operate during normal operation of said
electronic device.
39. An electronic device comprising: means for detecting a power
supply failure; and means for adjusting a clock frequency of said
electronic device in response to said power supply failure.
40. The electronic device of claim 39, wherein said means for
adjusting a clock frequency decreases said clock frequency in
response to said power supply failure.
41. The electronic device of claim 39, wherein said electronic
device is a computer.
42. The electronic device of claim 39, wherein said electronic
device is an integrated circuit.
43. The electronic device of claim 39, wherein said means for
adjusting a clock frequency includes a phase-locked loop.
44. The electronic device of claim 39, wherein said means for
measuring a power supply voltage and said means for adjusting a
clock frequency automatically operate during normal operation of
said electronic device.
45. An electronic device comprising: a system configuration
register; a clock controller electrically coupled with said system
configuration register, wherein said clock controller receives
configuration data from said configuration register and produces
clock signals of varying frequencies in response to said
configuration data; and a fan failure detector electrically coupled
with said clock controller, wherein said clock controller receives
fan data from said fan failure detector and produces clock signals
of varying frequencies in response to said fan data.
46. The electronic device of claim 45, further comprising: a power
supply failure detector electrically coupled with said clock
controller, wherein said clock controller receives power supply
data from said power supply failure detector and produces clock
signals of varying frequencies in response to said power supply
data.
47. An electronic device comprising: a system configuration
register; a clock controller electrically coupled with said system
configuration register, wherein said clock controller receives
configuration data from said configuration register and produces
clock signals of varying frequencies in response to said
configuration data; and a power supply controller electrically
coupled with said system configuration register, wherein said power
supply controller receives configuration data from said
configuration register and sets a power supply to varying voltages
in response to said configuration data.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to the field of computer
hardware and more specifically to the field of the automatic
adaptation of computer hardware to its environment.
BACKGROUND OF THE INVENTION
[0002] Modern computer systems typically comprise a number of
integrated circuits and other active electronic devices. These
integrated circuits are generally fabricated from a semi-conductor
material such as silicon and encapsulated in an integrated circuit
package for attachment to a printed circuit board. It is well known
in the art of integrated circuits and computer systems that the
circuits' maximum possible performance may be correlated to the
temperature of the device itself. The temperature of the device is
driven by the ambient temperature of the air surrounding the
device, the altitude of the device, airflow across the device, and
self-heating of the device itself during operation. Most integrated
circuits may be operated at higher speeds in a cool environment
than in a hot environment. When integrated circuits are tested,
often some portion of the test is performed at an elevated
temperature simulating the maximum allowable temperature during
operation in order to provide assurance that the circuit will work
properly at its maximum speed in an environment including its
maximum allowable temperature. Often, the same device will be
capable of performing properly at greater speeds in environments
that include temperatures lower than its maximum allowable
temperature.
[0003] It is also well known in the art of integrated circuits and
computer systems that these electronic devices produce heat during
their normal operation. Most integrated circuits produce more heat
at higher operating frequencies than they do at lower operating
frequencies. In many computer systems comprising one or more
integrated circuits, cooling these integrated circuits is necessary
to insure an operating environment within the allowable temperature
range. Cooling may be accomplished in a variety of methods. Many
computer systems include fans to move air across the integrated
circuit packages. Some integrated circuit packages include heat
sinks to help dissipate heat from the integrated circuit through
the package and heat sink and into the air moving across the heat
sink. Other integrated circuit packages, particularly for circuits
dissipating large amounts of power, include channels for water or
another liquid to flow through the package removing heat from the
circuit. Still other integrated circuits are cooled by immersion
cooling, spray cooling, and micro-channel cooling on the actual
silicon die.
[0004] In addition to the desire to control the environment within
a computer system, there is a desire to control the environment
surrounding the computer system since the fans in a typical
computer system simply take air from the environment surrounding
the computer system and move it across the electronic devices. If
the air surrounding the computer system is very warm, this warm air
may be all that is available to cool the computer system and
because of the higher ambient temperature, the devices within the
computer system may operate at a higher temperature. When large
numbers of computer systems are placed in physical proximity to
each other, cooling the surrounding air may become critical to
ensure that the devices inside each of the computer systems are
operating within their temperature specifications. Thus, many users
of multiple computer systems place the computer systems together in
one room or area that may be cooled sufficiently to allow operation
of all of the computer systems within their temperature
specifications. These special rooms are often called `data
centers.`
[0005] Many data centers include special refrigeration equipment
that cools the air within the data center to a level insuring the
proper operation of the computer systems within the data center.
This special equipment is necessary since many computer systems
produce large amounts of heat during operation and without the
additional refrigeration equipment, the normal building air
conditioning might be unable to remove enough of this heat from the
air to allow the computer systems to operate within their
temperature specifications. Other facilities include liquid
refrigeration equipment plumbed to the computer systems to provide
liquid cooling to the devices within the computer systems.
[0006] Problems arise when portions of this refrigeration equipment
breaks down. The cooling capacity of the refrigeration equipment
may be reduced and the air within the data center may rise above
the maximum temperature allowed by the computer systems. Most
computer systems run at a fixed clock frequency. When the device
temperature of their integrated circuits rise, the actual switching
capacity of the integrated circuits slows down. Since the latches
or registers of these circuits are clocked at a fixed frequency,
when the switching slows down too far, the latches and registers
may set before their inputs arrive causing them to store incorrect
data. This incorrect data may culminate in incorrect results or may
cause the computer to shut down and require a reboot.
[0007] Other data center problems may arise when the data center is
not properly designed, or is used outside of its capabilities. If
proper airflow is not maintained through out the data center, some
of the computer systems may have a higher ambient air temperature
than other systems. When computer systems are placed in close
proximity to each other, it is possible that the air intake of one
machine may be very near the outflow of an adjacent machine that
may flow hot air into the air intake, causing over-heating. The
warmer computer systems may be more prone to failure than the
cooler systems.
[0008] Some computer systems include temperature-sensing circuitry
controlling fans within the system. When the temperature rises,
these systems increase fan speed to better cool the electronic
devices. As the temperature falls, these systems decrease fan speed
to save power and reduce the noise of the system fans. However,
these systems can only move a limited quantity of air over their
circuits and are dependant on the outside environment for their
cool air. If the outside environment is too warm, it is possible
that the temperature within the computer system will continue
rising beyond the cooling capability of the system fans. Once the
internal temperature rises above the maximum allowable temperature,
the computer system may give a warning and then shut itself down to
prevent computing errors or possible damage to the system. Further,
reliability may be reduced when computer systems are operated at
temperatures outside of their ranges. It is well known in the art
that metal migration within integrated circuits increases at
elevated temperatures and over time. The longer an integrated
circuit is run at an elevated temperature, the greater the chances
that a physical failure of the device will occur. Thus, it is
desirable to prevent overheating of integrated circuits for
extended periods of high temperature operation whenever
possible.
[0009] Another problem with air-cooled computer systems is that at
high elevations, the air is less dense and therefore less efficient
in conducting heat away from the devices. Computer systems must be
designed to operate properly at high elevations while the vast
majority of users never operate their computer systems in such an
environment. Thus, a computer system designed to work at 10,000
feet elevation may have the ability to perform at a higher
frequency at sea level due to the better cooling capabilities of
the dense air at sea level. This computer system used at sea level
would then be performing below its actual capabilities, depriving
the user of some portion of its performance capabilities.
[0010] Many computer systems include extra fans to allow a margin
of safety in the event of one or more of the fans failing. Also,
many data centers are designed to include extra refrigeration
capacity allowing an additional margin of safety in the event that
one of the refrigeration units fails. However, even with these
precautions, failures still occur, causing the air temperature to
rise above the maximum allowed by the computer systems. In these
situations, the computer servers may perform improperly or shut
down and require a reboot, causing great difficulty for their
users. Also, it is possible that a fan failure would result in a
heat rise in one part of the system and not another.
[0011] Along with extra fans, some computer systems include extra
power supplies to provide sufficient power to the system should one
or more of the power supplies fail. However, these precautions are
very costly and even if used, may still not be sufficient to allow
for full performance of the computer system in the event of one or
more failures. For example, a system built with one extra power,
may have two power supply failures, and not have sufficient current
capability remaining to power the system at maximum
performance.
SUMMARY OF THE INVENTION
[0012] An electronic device such as a computer, circuit board, or
integrated circuit is built including circuitry for receiving
temperature information. The clock frequency of the electronic
device is varied in response to the temperature of the electronic
device, thus lowering speed and power consumption of the device
during periods of higher than normal temperature. Alternately, an
electronic device such as a computer, circuit board, or integrated
circuit is built including circuitry for receiving power supply
information. The clock frequency and possibly the power supply
voltage of the electronic device is varied in response to the power
supply status of the electronic device, thus lowering speed and
power consumption of the device during periods of lower than normal
power supply current capability.
[0013] A computer may be designed without extra fans or power
supplies, thus reducing the cost of the computer. When a failure
occurs in one of the fans or power supplies, the integrated
circuits detect the failure and reduce their clock speeds and
possibly their power supply voltage automatically in response to
power supply failures, cooling equipment failures, altitude,
temperature, and other environmental factors. This allows the
computer to continue to operate at a slower frequency, but without
any loss of data and no need to restart any applications running on
the computer. This is especially important for critical servers
where an error or failure may be very costly to the user.
[0014] Also, if a computer system were able to automatically detect
environmental cooling capabilities, it would be possible to design
a computer system for full performance at sea level, yet the
computer system could automatically adjust for slightly less
performance at altitude to allow for the less efficient cooling at
high elevations.
[0015] Further, if a computer system were able to automatically
detect and make allowances for environmental conditions on an
individual integrated circuit basis, only part of the computer
system would suffer reduced performance due to the environmental
conditions.
[0016] Other aspects and advantages of the present invention will
become apparent from the following detailed description, taken in
conjunction with the accompanying drawings, illustrating by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a block diagram of an example embodiment of an
electronic device including a temperature-controlled clock
according to the present invention.
[0018] FIG. 2 is a block diagram of an example embodiment of an
electronic device including a power supply failure sensitive clock
according to the present invention.
[0019] FIG. 3 is a waveform diagram of an example embodiment of a
temperature-controlled clock according to the present
invention.
[0020] FIG. 4 is a waveform diagram of an example embodiment of a
power supply failure sensitive clock according to the present
invention.
[0021] FIG. 5 is a waveform diagram of an example embodiment of a
temperature-controlled clock according to the present
invention.
[0022] FIG. 6 is a waveform diagram of an example embodiment of a
power supply failure sensitive clock according to the present
invention.
[0023] FIG. 7 is a flowchart of an example embodiment of a method
for temperature controlling a clock according to the present
invention.
[0024] FIG. 8 is a flowchart of an example embodiment of a method
for temperature controlling a clock according to the present
invention.
[0025] FIG. 9 is a flowchart of an example embodiment of a method
for controlling a clock and power supply according to the present
invention.
[0026] FIG. 10 is an example embodiment of a computer system
including a self-adjusting clock according to the present
invention.
DETAILED DESCRIPTION
[0027] FIG. 1 is a block diagram of an example embodiment of an
electronic device 100 including a temperature-controlled clock
according to the present invention. An electronic device 100 such
as a computer, a printed circuit board, or an integrated circuit is
built including a temperature sensor 102. This temperature sensor
102 may be implemented in a variety of different ways within the
scope of the present invention. If the electronic device 100 is a
computer or printed circuit board, the temperature sensor 102 may
be a simple thermocouple that translates temperature to a voltage
value. If the electronic device 100 is a single integrated circuit,
the temperature sensor 102 may be a thermal diode fabricated within
the integrated circuit. The temperature sensor 102 outputs a
temperature signal 104. This temperature signal 104 may be a
voltage or it may comprise digital data within the scope of the
present invention. The temperature signal 104 is input to a clock
controller 114. The clock controller 114 uses the temperature
signal 104 to determine a frequency of operation. The clock
controller 114 outputs a clock signal 116 for use by electronic
circuits 118 within the electronic device 100. Those of skill in
the art will recognize that a clock controller 114 may be comprise
a phase-locked-loop, and the phase-locked-loop may be digital in
some embodiments of the present invention. In an example embodiment
of the present invention, as the temperature of the electronic
device 100 rises, this temperature rise is reflected in the
temperature data 104 received by the clock controller 114 and the
frequency of the clock signal 116 is reduced as the temperature
rises. As the temperature of the electronic device 100 cools, the
clock controller 114 increases the frequency of the clock signal
116. In another example embodiment of the present invention, a
system configuration register 110 contains information about the
configuration of the electronic device 100 such as the number of
fans available and their speed. System configuration data 112 is
supplied to the clock controller 114 that then may respond to the
configuration data 112 by changing the clock frequency, or waiting
for a rise in temperature before adjusting the clock frequency. In
another example embodiment of the present invention, a fan failure
detector 106 may be used to send fan data 108 to the clock
controller 114 that then may respond to the fan data 108 by
changing the clock frequency, or waiting for a rise in temperature
before adjusting the clock frequency. Variables such as any delay
before changing the clock frequency, how much the clock frequency
is allowed to vary, and response times of the clock may be
determined by the designer of an embodiment of the present
invention, all within the scope of the present invention.
[0028] FIG. 2 is a block diagram of an example embodiment of an
electronic device 100 including a clock controller 208 and a power
supply controller 204 according to the present invention. An
electronic device 100 such as a computer, a printed circuit board,
or an integrated circuit is built including a power supply failure
detector 200. This power supply failure detector 200 may be
implemented in a variety of different ways within the scope of the
present invention. If the electronic device 100 is a computer or
printed circuit board, the power supply failure detector 200 may be
a signal from the power supply that is activated when the power
supply goes into a failure mode, such as a current-limiting mode.
The power supply failure detector 200 outputs a power fail signal
is 202. This power fail signal 202 may be a single bit signal, or
it may comprise more complex digital data within the scope of the
present invention. The power fail signal 202 is input to a clock
controller 206 and a power supply controller 204. The clock
controller 206 uses the power fail signal 202 to determine its
frequency of operation. The clock controller 206 outputs a clock
signal 116 for use by electronic circuits 118 within the electronic
device 100. The power supply controller 204 uses the power fail
signal to change the power supply voltage in response to power
supply failures. For example, in a system comprising multiple power
supplies, where one of the supplies fails, the remaining supplies
may not have enough current capability to continue supplying the
system with full voltage. In this case, it may be desired to reduce
both the clock frequency and the power supply voltage in response
to the failure since both heat and power consumption are
proportional to the power supply voltage squared. Thus, a small
decrease in power supply voltage may have a large effect on the
power consumption of the electronic circuit 118. In another example
embodiment of the present invention, a system configuration
register 110 contains information about the configuration of the
electronic device 100 such as the number of power supplies
available and their status. System configuration data 112 is
supplied to the clock controller 206 and the power supply
controller 204 that then may respond to the configuration data 112
by changing the clock frequency and power supply voltage, or
waiting for a change in device temperature before adjusting the
clock frequency and power supply voltage. In another example
embodiment of the present invention, a power supply failure
detector 200 may be used to send power supply data 202 to the clock
controller 208 and the power supply controller 204 that then may
respond to the power supply data 202 by changing the clock
frequency and power supply voltage, or waiting for a change in
device temperature before adjusting the clock frequency and power
supply voltage. Some embodiments of the present invention may allow
only the clock frequency to be varied instead of both the power
supply voltage and the clock frequency. Variables such as any delay
before changing the clock frequency, how much the clock frequency
is allowed to vary, and response times of the clock may be
determined by the designer of an embodiment of the present
invention, all within the scope of the present invention.
[0029] FIG. 3 is a waveform diagram of an example embodiment of a
temperature-controlled clock according to the present invention.
The time axis 300 shows increasing time from left to right,
including two specified times t0 306 and t1 308. Above the time
axis 300 are drawn a clock signal 302 and a temperature 304. At
time t0 306 the temperature 304 is steady and the clock signal 302
is at a steady frequency. At time t1 308 the temperature 304 rises
and the frequency of the clock signal 302 decreases in response. In
the example embodiment of the present invention corresponding to
FIG. 3, the clock frequency changes by a factor of two. This is for
illustrative purposes only as the clock frequency may change by any
factor (or continuously) within the scope of the present
invention.
[0030] FIG. 4 is a waveform diagram of an example embodiment of a
power supply failure sensitive clock according to the present
invention. The time axis 300 shows increasing time from left to
right, including two specified times t0 404 and t1 406. Above the
time axis 300, are drawn a clock signal 302 and a power supply
voltage 402 at some voltage level above ground 400. Also, above the
power supply voltage 402 is a line representing the maximum power
supply current available 408. At time t0 404 the maximum power
supply current available 408 is steady and the clock signal 302 is
at a steady frequency. At time t1 406 the maximum power supply
current available 408 decreases and the frequency of the clock
signal 302 decreases in response. Also, the power supply voltage
402 decreases in response to the decreased supply current available
408. In some example embodiments of the present invention, it may
be desired to only change the clock frequency and not adjust the
power supply voltage levels. However, since heat and power
consumption vary with the square of the power supply voltage, a
small change in supply voltage may have a large change in heat and
power consumption. In the example embodiment of the present
invention corresponding to FIG. 4, the clock frequency changes by a
factor of two. This is for illustrative purposes only as the clock
frequency may change by any factor (or continuously) within the
scope of the present invention.
[0031] FIG. 5 is a waveform diagram of an example embodiment of a
temperature-controlled clock according to the present invention.
The time axis 300 shows increasing time from left to right,
including three specified times t0 500, t1 502, and t2 504. Above
the time axis 300 are drawn a clock signal 302 and a temperature
304. At time t0 500 the temperature 304 is steady and the clock
signal 302 is at a steady frequency. At time t1 502 the temperature
304 rises and the frequency of the clock signal 302 decreases in
response. At time t2 504 the temperature 304 returns to its
previous level and the frequency of the clock signal 302 increases
back to its previous rate in response to the change in temperature
304. In the example embodiment of the present invention
corresponding to FIG. 5, the clock frequency changes by a factor of
two. This is for illustrative purposes only as the clock frequency
may change by any factor (or continuously) within the scope of the
present invention.
[0032] FIG. 6 is a waveform diagram of an example embodiment of a
power supply failure sensitive clock according to the present
invention. The time axis 300 shows increasing time from left to
right, including three specified times t0 600, t1 602, and t2 604.
Above the time axis 300, are drawn a clock signal 302 and a power
supply voltage 402 at some voltage level above ground 400. Also,
above the power supply voltage 402 is a line representing the
maximum power supply current available 408. At time t0 600 the
maximum power supply current available 408 is steady and the clock
signal 302 is at a steady frequency. At time t1 602 the maximum
power supply current available 408 decreases and the frequency of
the clock signal 302 decreases in response. Also, the power supply
voltage 402 decreases in response to the decreased supply current
available 408. At time t2 604 the maximum power supply current
available 408 returns to its previous level and the frequency of
the clock signal 302 increases back to its previous rate in
response to the change in maximum power supply current available
408. Also, the power supply voltage 402 increases back to its
previous level in response to the increased supply current
available 408. In some example embodiments of the present
invention, it may be desired to only change the clock frequency and
not adjust the power supply voltage levels. However, since heat and
power consumption vary with the square of the power supply voltage,
a small change in supply voltage may have a large change in heat
and power consumption. In the example embodiment of the present
invention corresponding to FIG. 6, the clock frequency changes by a
factor of two. This is for illustrative purposes only as the clock
frequency may change by any factor (or continuously) within the
scope of the present invention.
[0033] FIG. 7 is a flowchart of an example embodiment of a method
for temperature controlling a clock according to the present
invention. In a step 700 a temperature value is read. In a step
702, after step 700, a new temperature value is read. In a step 704
the new temperature value is compared to the old (or previous)
temperature value. In a decision step 706, if the temperature has
not changed, control is given to step 702 and a new temperature
value is read and the loop is repeated until the temperature
changes. If the temperature has changed control is given to a
decision step 708 where the method determines if the temperature
has increased or decreased. If the temperature has increased, in a
step 710, the clock frequency is decreased and control is passed
back to step 702 for a new temperature reading. If the temperature
has decreased, in a step 712, the clock frequency is increased and
control is passed back to step 702 for a new temperature reading.
The sampling rate of the configuration register may be continuous
or determined by other factors within the scope of the present
invention.
[0034] FIG. 8 is a flowchart of an example embodiment of a method
for temperature controlling a clock according to the present
invention. In a step 800, a system configuration register 110 is
read. This system configuration register 110 may contain
information about the system such as the number of fans in
operation, altitude of the system, number of processors, airflow
requirements of the processors and other information about how the
system is configured. Note that various embodiments of the present
invention may include a variety of data in the system configuration
register 110 within the scope of the present invention. In some
embodiments of the present invention, there may not be a separate
register containing this information, but the information is
obtainable from other latches or registers throughout the system.
In a step 802, the method checks for fan failures. This fan failure
information may be contained within the system configuration
register, or its equivalents, or it may be received from other
mechanisms configured to detect fan failures. In a decision step
804, the system configuration data and fan failure data is analyzed
to determine if the system, in its current configuration has
sufficient cooling capability to maintain the circuits within their
specified temperature ranges. If so, control loops back to step
800, and the process is repeated. If the system does not have
sufficient cooling capability, the device temperature is checked in
a step 806. In a decision step 808 the device temperature is
compared to the operating limits of the device. If the device
temperature is within the operating limits, control loops back to
step 806, and the temperature is monitored within this loop until
it exceeds the operating limits. If the device temperature is not
within the operating limits, the clock speed is adjusted in a step
810. After adjusting the clock speed, control is returned to step
800 and the system monitoring continues. In some embodiments of the
present invention, after the determination is made that the system
does not have sufficient cooling capability to operate, the clock
speed is immediately adjusted to account for the cooling capability
of the system without going through the step of checking device
temperature against the device specifications. If the results of a
fan failure are known or calculable by the system, there is no need
to check device temperatures before reacting to a fan failure. The
sampling rate of the configuration register may be continuous or
determined by other factors within the scope of the present
invention.
[0035] FIG. 9 is a flowchart of an example embodiment of a method
for controlling a clock and power supply according to the present
invention. In a step 900, a system configuration register 110 is
read. This system configuration register 110 may contain
information about the system such as the number of power supplies
in operation, the output voltage and current of each of the
supplies, number of processors, voltage requirements of the
processors and other information about how the system is
configured. Note that various embodiments of the present invention
may include a variety of data in the system configuration register
110 within the scope of the present invention. In some embodiments
of the present invention, there may not be a separate register
containing this information, but the information is obtainable from
other latches or registers throughout the system. In a step 902,
the method checks for power supply failures. This power supply
failure information may be contained within the system
configuration register, or its equivalents, or it may be received
from other mechanisms configured to detect power supply failures.
In a decision step 904, the system configuration data and power
supply failure data is analyzed to determine if the system, in its
current configuration has sufficient voltage and current capability
to maintain the circuits within their specified voltage ranges. If
so, control loops back to step 900, and the process is repeated. If
the system does not have sufficient power, the temperature is
checked in a step 806. In a decision step 808 if the temperature is
within the limits, control is returned to step 806 for further
monitoring of the temperature. If the device temperature is not
within the operating limits, the clock speed and power supply
voltage are adjusted in a step 906. After adjusting the clock speed
and power supply voltage, control is returned to step 900 and the
system monitoring continues. In some embodiments of the present
invention, after the determination is made that the system does not
have sufficient power to operate, the clock speed is immediately
adjusted to account for the voltage and current capability of the
system without going through the step of checking device voltage
against the device specifications. If the results of a power supply
failure are known or calculable by the system, there is no need to
check device temperatures before reacting to a power supply
failure. The sampling rate of the configuration register may be
continuous or determined by other factors within the scope of the
present invention.
[0036] FIG. 10 is an example embodiment of a computer system
including a self-adjusting clock according to the present
invention. In an example embodiment of a computer system including
the present invention, a computer chassis 1000, including at least
one power supply 1008 and at least one fan 1010 is built including
at least one electronic circuit containing a self-adjusting clock
according to the present invention. The computer receives input
from the user via a mouse 1006 and a keyboard 1004 and outputs
information or graphics to a display 1002. Many other uses of the
present invention will be apparent to those of skill in the art,
this is but one example usage of the present invention.
[0037] The foregoing description of the present invention has been
presented for purposes of illustration and description. It is not
intended to be exhaustive or to limit the invention to the precise
form disclosed, and other modifications and variations may be
possible in light of the above teachings. The embodiment was chosen
and described in order to best explain the principles of the
invention and its practical application to thereby enable others
skilled in the art to best utilize the invention in various
embodiments and various modifications as are suited to the
particular use contemplated. It is intended that the appended
claims be construed to include other alternative embodiments of the
invention except insofar as limited by the prior art.
* * * * *